Challenging Question: Roots

[Checked: 21 Jan 2020]

Should not apply estimation as it will introduce greater error margin.

The method is you take the last digit of the number, 9870

Which is 0

Then ignore the last 3 numbers.

Which leads us to number 9.

The closest cube number is 8.

The root of 8 is 2

Put 2 in front of 0, which was the last digit of 9870.

Thus the answer is 20

(estimated)